Thursday, April 16, 2009

New mosaic maps released

GeoSage has announced the release of near-global imagery mosaics on shaded relief and natural-colour satellite imagery. Each mosaic map is a single large-sized, GIS-ready JPEG2000 file, and it can be obtained on DVDs or external hard drives.

Seamless 90m-resolution hillshading maps are derived from the USGS SRTM data set. More than 14,000 raw SRTM tiles are first stitched into a single large mosaic (image size 432,000 by 139,200 pixels) with elevation gaps filled, and then a series of shaded-relief maps are cartographically designed and produced under various colour schemes and different hillshading settings.

Seamless 60m- and 90m-resolution satellite imagery mosaics are derived from the 30m-resolution Earth Land Surface 2000 imagery product, which consists of more than 880 regional tiles for the globe. These two imagery mosaics have the image sizes of 648,000 by 270,000 pixels and 432,000 by 180,000 pixels, respectively. Raw mosaics with the file sizes of a few hundreds of gigabytes are compressed into efficient and accessible JPEG2000 format.


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